Wash and dry all produce. Take out cream cheese from refrigerator and set aside. Cut half the broccoli into small pieces. Mince or grate garlic. Zest lemon until you have 2 tsp zest, then cut into halves. Squeeze juice into a small bowl. Pick basil leaves from stems; discard stems. Roughly chop leaves.

Pat chicken dry with a paper towel, then cut into 11/2-inch pieces. Heat a large drizzle of olive oil in a large pot over medium-high heat. Season chicken all over with salt and pepper. Add to pot along with garlic. Cook, tossing occasionally, until browned all over, 3-5 minutes. Remove from heat and transfer chicken to a large bowl.

Add lemon juice to empty pot, scraping up any brown bits from bottom. Pour over chicken in bowl and set aside. Add stock concentrates, 4 cups water, and gemelli to pot and give it a stir. Bring to a boil over high heat, then lower heat to medium and reduce to a simmer. Cook, stirring frequently, for 8 minutes.

Stir chicken and juices from bowl into pot with pasta, along with broccoli and peas. Cook until chicken is no longer pink in center, broccoli is just tender, and gemelli is al dente, 4-5 minutes.

Stir cream cheese, lemon zest, half the Parmesan, and half the basil into pot. Keep stirring until cheeses melt and a creamy sauce has formed. Season with salt and pepper.

Divide pasta mixture between plates. Sprinkle with remaining basil and Parmesan and serve.